Hydraulically set, releasable well packer



March 2, 1965 c. B. COCHRAN HYDRAULICALLY SET, RELEASABLE WELL PACKER 2 Sheets-Sheet l Filed Oct. 9, 1961 n vVENToR.

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ATTORNEYS March 2, 1965 c. B. cocHRAN v HYDRAULICALLY SET, RELEASABLE WELL PACKER 2 Sheets-Sheet 2 Filed Oct. 9, 1961 CHUDLE/GH B 00CHF/W INVENTOR.

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ATTORNEYS United States Patent 3,171,492 HYDRAULICALLY snr, RELEASABLE WELL PACKER Chudleigh B. Cochran, Houston, Tex., assigner to Cicero C. Brown, Houston, Tex. Filed Get. 9, 1961, Ser. No. 143,686 1t) Claims. (Cl. 166-187) This invention relates to well packers for use in the operation of oil wells, and more particularly to a Well packer which is designed to be set by hydraulic pressure and which may be easily released yby mechanical manipulation of a tubing string.

In the operation of oil wells, it is frequently desirable to be able to isolate formations located at different depths to permit `the same to be separately produced. Under some conditions it is also desirable to provide means by which production may be carried on selectively from any of a number of locations at different levels in a well.

The present invention has for an important object the provision of a well packer which is designed to be applied to a tubing string for insertion therewith in a well casing and which is operable by the pressure of fluid in the tubing to pack oli the iannulns between the tubing and casing `at a desired location.

Another object of the invention is to provide well packer mechanism which is operable by the application of pressure iluid to a well tubing to set the packer and which is operable by rotational movement of the tubing to release the packer.

A further object `of the invention is the provision in a well packer of seal forming means of improved construction which is designed to obtain an increased pressure holding force under the iniiuence of a smaller expanding or setting force than has been possible heretofore with the use of seal forming means of the usual type.

Another object of the invention is to provide well packer mechanism embodying a number of packers connected into a tubing string at longitudinally spaced intervals and havmg means for setting the packers by the introduction of luid under pressure into the string and means whereby the packers may `be independently released las desired by mechanical manipulation of the string.

A further object of the invention is the provision of Well packer mechanism which is designed to be set by fluid pressure and including means for releasably holding the packer in a set condition independently of the pressure which is applied to set the same.

Another object of the invention is the provision in well packer mechanism of improved seal forming means` in an annulus between a well tubing and a casing surrounding the same for expansion finto sealing contact with the tubing and casing to pack off the annulus and embodying a central, radially inwardly tapering seal element, and upper and lower radially outwardly bevelled seal elements above and belo'w said central element, in position for coaction with said central element to form oppositely directed seal forming cups upon setting of the packer by relative longitudinal movement of the elements.

In many Well installations it is desirable to set a plurality of packers in a pipe string in order to seal off the well bore between several dilferent producing horizons. In such installations it is often desirable and necessary to initially connect the lower end of the pipe carrying Such a string of packer into a permanently set bottom packer previously placed in the well bore, and to thereafter release the string from the bot-tom packer to adjust the total length of the pipe string before hanging the latter in the well head. Release from the bottom packer SZEZ Patented Mar. 2, 1965 is conventionally effected by right-hand rotation of the pipe string but this cannot be accomplished with pipe strings employing the more conventional types of pac (ers without setting the packers or after the packers have been set.

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Accordingly, it is an additional important object of this invention to provide a packer structure which permits rotation of the pipe string without setting the packers and which when the packers have been set is operative by `right-hand rotation of the pipe string to successively release the packers and extend rotation of the pipe string through its full length to the bottom packer.

A further additional object is the provision of a fluid pressure actuatable packer structure employing ya novel form of clutch mechanism between the supporting pipe string and packer body which is releasable by the setting of the packer to release the pipe string for rotation relative to Ithe packer body whereby to release the packer and to transfer the releasing rotation downwardly successively to other similar packers mounted in the pipe string.

In fluid pressure actuated packers, it is desirable to provide means to prevent reverse slippage or retraction of lthe packers when they have been set, as may often occur due to jarring of the pipe string or reversals in pressure differentials .across the packers. Some prior art arrangements have employed small internal slips mounted between the packer compression members or cones and the packer mandrel which are urged into wedging engagement by springs to effect the desired anchoring function. However, these spring-urged slips have proved unsatisfactory in that often they will slip back under the forces to which they are subjected, the springs employed being ineffective to drive the slip teeth sufficiently strongly into the mandrel surface to effectively oppose the unseating forces.

Accordingly, it is a `further important object in accordance with this invention to provide an anti-retraction mechanism for packers which is `actuated by fluid-pressure.

A more specific object is the provision of a fluid pressure actuated anchor mechanism, for the purpose indicated, employing a plurality of toothed wedge slips and a positive drive means therefor actuated by iluid pressure which may be the fluid pressure employed in setting the packer itself.

A still further object of the invention is to provide well packer mechanism of the type referred to which is of strong and rugged construction and in which the parts are easily replaceable for purposes of maintenance and repair.

The above and other important objects and advantages of the invention will be apparent from the following detailed description, constituting a specification of the invention when taken with the annexed drawings, wherein- FIGURE l is a fragmentary, side elevation view, partly in cross-section showing a portion of a well with a well casing and tubing string therein and illustrating a preferred embodiment of the packer of the invention in re leased condition prior to the setting of the packer in the well;

FIGURE 2 is a view similar to that of FIGURE l illustrating the packer of the invention in set position;

FIGURE 3 is a View similar to that of FIGURE 2 showing the packer of the invention after releasing of the same;

FIGURE 4 is a cross-sectional View, taken along the line 4 4 of FIGURE 1, looking in the direction indicated by the arrows;

FIGUREl 5 is a cross-sectional view, taken along the line 5-5 of FIGURE l, looking in the direction indicated by the arrows; and

FIGURE 6 is a cross-sectional view, taken along the line 6-6 of FIGURE l, looking in the direction indicated by the arrows. j

Referring now to the drawings in greater detail, the well packer of the invention is illustrated in'connection with its use in a well bore having the usual casing C, which may extend to any desired depth in the well, and maybe suitably perforated at locations to permit 4the production of oil or gas from various formations `atadifferent depthsin the well. f. f Y

The well packer arrangement of the invention includes one or more packer assemblies, generally designated "P, which are connected -into a well tubing, generally Y,designated T, for insertion therewith intor the-'casing rto be expanded thereinY to pack .olf-the. annulus A, between the casing and tubing at locations to permit therproduction of the well from any desired formation therein.` It will a'downwardly opening, annular, tapered recess 60, within which externally toothed .arcuate wedges 64 are slidably received. These wedges normally'projectslightly below the lower end lof the lower back-upY ring. Within the chamber 50 an annular piston 66 is slidably disposed in vsurrounding relation to the mandrel 10 and is provided Y with suitable seal forming means ,suchas the O-rings 68,

' 'v to form fluid-tight'seals between the mandrel and piston be understood that such packer Vassemblies will be inter-V which communication may be established between the tubing and any selected producingvforma'tion. Y

Each ofthe packer assemblies comprises an `inner tubular body or mandrel l0, Vwhoselower, end isv externally threaded, as indicated at '12 for threadable connection The upper end ofthe mandrel 10 extendsinto a couv pling'formed in two threadably connected parts Y22 and 24, v.the partf22 beinginternally-threaded at its upper end, as indicated at 26, for connectionrto, the externally spersed with conventional sleeve valvesV (not shown) Vby wardly.

and ybetween the piston and sleeve 48. The piston 66 is engageable directly with the wedges 64 to move the wedges upwardly in the recess 60'upon "upward movement of the piston in the chamber50 to force the wedge teeth tightly into. the external surface of mandrel 10.

The mandrel has a port 70 leading from the interior of the mandrel into the vchamber 50 beneath the piston 66 and through .which fluid under pressure in the tubing string may enter the chamber 50 to move the piston 66111)- Between the upper and lower back-up rings 38 and 46, upper and lower annular, expansible packerl elements 72 and '74 surround the,.mandrel 10- and between these elements ra central, expansible" annular, wedge shaped packer element V76 is located. The packer .element 76 i tapersV radiallyinwardly and the upper. and lower ele- V'ments '72 and 74 yare, each formedwith a radially bevelled, face positioned lfor engagement with one of the tacompressionbetween theupper and lowery back-up rings,

threaded lower end of anupper section 28 ofthe tubing f T, and internally threaded at itslower end, as indicated att), for connection to the part 24.l The lmandrell() Ais provided with external, coarse threads 3 2, near Yits upper end, and the part 24 is similarly provided ,with internal,

the elements willbe compressed into sealing contact with the mandrel and ,well casingto seal ,off the annulus there- Y betweemf During such endwise yor longitudinal compression fof the packer elements, the elements 72 and 74 are compressed against the tapering facesof the ,central element 76-,to form two foppositely directed cup like portions which -openaway from each other, as seen in FIG- URE 2, whereby fluid is prevented from becoming trapped coarse threads whereby Lthe mandrelis `connected to ,the Y tubing T through the coupling. The mandrel is thus` connected into and becomes a part of the tubingvstring.

At its lower end the part 24 is provided Awith Acircurn- Y ferentially spaced, external projectionst, between which internal, circumferentiallyspaced ,projections V36V on an upper back-up ring or upper abutment member 38 are slid-l ably received to forma clutch 'connecting the ring to the' part 24for rotation therewith. The clutch is 'releasably held in its engaged position by suitable means such as the shear pinsflt). The mandrel :1Q is alsoiformed with external, longitudinal groovesr42,into which theinner end s of screw-pins 44, carried by the back-up ring38'are slidably extended to,ho.ld the backeup ring against rota-` tion relative yto the mandrel.

A lower back-.up ring or lower` abutment member Y46 surrounds 4the mandrel 10 in longitudinally spaced relation thereon below the upper back-.upring, and an `external sleeve 48 is lattached at its upper end to the Alower back-up ring, as by means of set screws 47,and extends downwardly therefrom in radially outwardlyvspaced relation Vto the mandrel to ,form yan annular chamber ,50 surrounding the mandrel. Y

The sleeve 4,8 is closed at its lower end by an annular therewith, ,by suitable means,.such as the internal ,split lock between the elements. v

The coupling part 22 has a port 7 8 leading fromthe annulus A into the interior of-thetubing stringand suitable packing means, such as that shownat 80, surrounds the upper-end of rthe mandrel, l'between the lower end ofthe CQllarlS and a ring 32 surrounding the mandrel 10 .Y shown in FIGURES 1 and 2, and to open the port 7,8 to

such i'now when the packer is released, as shown in FIG- URE 3.` Y Y Y Thepacker'mechanismV of theV invention is set by the pressure of fluid in the tubing T, and for this purposesuitable means, such `as a ballor other. similar device, indicatedby. the ldotted line `/84in FIGURE 2,.is inserted in thegupperl end of the tubing-and allowed to move downwardly therein into closing engagement with an internal seatpnot shown, in thevtubing located below the lower- -most one of the `packer assemblies, to close the rtubing against the downward llowofgtluid therethrough.

In` making use of .the invention, constructed as de- `scribed above, ,the tubing T is'lowe'red into the well bore rings 54 Aand 55 which tit into suitable annular ,recesses f provided for the same in the'mandrel and member. The

sleeve 48 is slidable on the member 52 and is releasably provided to forrnfluidtight seals, respectively, between the mandrel and member 52 land between-the member and sleeve 48. Y

The lower back-up ring .46 yisV 'internallybevelled to form' withpnevor more Yof the .packer assemblies connected into the tubing string at longitudinally spaced intervals, accordingto the locations of the formations inthe well from'which it`may `be desired `to produce the Well, the

kpacker yasSP-rllbli es:being in ,their released condition, and

toY release the string from a bottom packer into-which the string has been connected -for rthe purpose of adjusting the length of the string before re-connecting the bottom packer and hanging in the tubing head. Thereafter, when the tubing string has been thus inserted in the well and set to the desired depth, the ball 84 is dnopped through the bore of the string to close the string at a location beneath the lowermost of the packer assemblies, and pressure lluid is pumped downwardly into the tubing string to set the packers.

During the setting of the packers, lluid under pressure in the tubing string may enter the chamber 50 of each packer assembly through the port 70 thereof, to move the lower pack-up ring 46 upwardly, to compress the packer elements 72, 74 and 76 longitudinally, the set-screws 56 being sheared by such pressure to allow the lower backup ring and sleeve 48 to move upwardly. During such expansion of the packer, the annular piston 66 will also be moved upwardly in the chamber 50 into direct engagement with the wedges 64, to positively force the wedges into the recess 60 in engagement with the inside tapering face of the lower back-up ring, as illustrated in FIG- URE 2, the wedges being thus forced strongly into gripping engagement with the external surface of the mandrel to hold the back-up ring against downward movement, whereby the packer elements will be held in their expanded condition to pack off the annulus between the tubing and the casing at the desired location. During the expanding of the packer, shear pins 40 of the upper backup ring will also be sheared to allow the upper back-up ring to move upwardly relative to the lower part 24 of the coupling, so that the clutch elements 34 and 36 will be disengaged, as shown in FIGURE 2.

With the packer assemblies thus set in the well casing, the packers may be released successively downwardly in the well, beginning with the uppermost packer assembly by rotating the tubing T, when it is desired to select any particular formation from which the well is to be produced.

During such rotation of the tubing with the packers set, the clutch elements 34 and 36 will be out of engagement so that the lower part 24 of the coupling will be rotated with the tubing and the external coarse threads 32 of the mandrel in engagement with the internal coarse threads of the coupling part 24 will cause the upper back-up ring 38 to move upwardly relative to the mandrel to allow the packer elements 72, 74 and 76 to relax, thus releasing the packer. Upon releasing the packer, the coupling part 22 will be moved to a position to uncover the port 78, so that the hydrostatic head in the tubing will be relieved by the inflow of fluid from the annulus A into the interior of the tubing.

Upon releasing the uppermost packer mechanism in the manner described above, the part 24 of the coupling will move to its uppermost limit on the coarse threads 32 of the mandrel, so that when the packer is released, the entire assembly may be rotated with the tubing T to opcrate the tubing to release the next lower packer assembly in the same manner. In this manner, the packers may be -successively released downwardly in the casing.

It is to be noted that during the setting of the packer mechanism, the radially inwardly tapering faces of the central element 76 will engage the adjacent tapering faces of the elements 72 and 74, so that as the packer is compressed, any lluid entrapped between the elements may escape longitudinally along the external surface of the mandrel and the internal surface of the casing, thus preventing interference of any such fluid with the effective sealing of the packer.

It will thus be seen that the invention, constructed and operated as described above, provides packer mechanism which is easily connected into an operating string of well tubing for insertion therewith into a well bore to be set therein at any desired depth, which is hydraulically operable to set the packer, and which may be readily released by rotation of the tubing string.

The invention is disclosed herein in connection with a certain specic embodiment of the same, but it will be understood that this is intended by way of illustration only and that numerous changes can be made in the construction and arrangement of the various parts, within the spirit of the invention and the scope of the `appended claims.

Having thus clearly shown and described the invention, what is claimed as new and desired to secure by Letters Patent is:

l. In a well packer, a tubing string, a tubular mandrel, thread means forming a rotatable connection between the mandrel and an upper section of the tubing string to cause relative longitudinal movement of the mandrel and said section upon rotation of the section relative to the mandrel, longitudinally spaced back-up rings surrounding and movable longitudinally on the mandrel, expansible packer means surrounding the mandrel between said rings, releasable means for holding one of said rings against movement relative to said mandrel, and pressure uid actuated means movably positioned on the mandrel to urge the other of said rings toward said one ring in response to the pressure of fluid in the string.

2. In a well packer, a tubing string, a tubular mandrel, means connecting the lower end of the mandrel to a lower section of the tubing string for rotation with said lower section, thread means forming a rotatable connection between the mandrel and an upper section of the string to cause relative longitudinal movement of the mandrel and said upper section upon rotation of the upper section relative to the mandrel, releasable clutch means for causing the mandrel to rotate with said upper section, longitudinally spaced back-up rings surrounding and movable longitudinally on the mandrel, expansible packer means surrounding the mandrel between said rings, pressure fluid actuated means movably positioned on the mandrel to urge said lower ring upwardly in response to the pressure of uid in the string, means forming a connection between said upper ring and said releasable clutch means to hold the upper ring stationaryk during upward movement of said lower ring to apply a compressive force to the packer means to expand the packer means and to release said releasable clutch means when 4the packer means is expanded, said upper ring being movable upwardly upon rotation of the upper section relative to said mandrel to allow the packer means to contract.

3. In a well packer a tubing string, means forming an expansible c-hamber surrounding and in fluid ilow communication with the interior of the string, a movable back-up ring surrounding the string and connected to said chamber means for longitudinal movement on the string upon expansion of the chamber and having yan internal annular bevellcd face positioned to form with the external surface of the string a tapered recess surrounding the string, a stationary back-up ring around the string in longitudinally spaced relation to said movable ring, wedge means movably mounted on the string for movement into a position in wedging engagement wit-h the string and movable ring in said recess to hold the movable ring against movement away from the stationary ring, means movably disposed in the chamber to move the wedge means to wedging position in response to the pressure of fluid in the string, and expansible packer means surrounding the string between said rings.

4. In a well packer a tubing string adapted to be inserted in a well bore, a sleeve member surrounding the string in radially outwardly spaced relation thereto, sta- -tionary means surrounding the string and closing one end of the sleeve member, a movable ring surrounding the string closing the other end of the sleeve member and movable therewith, said stationary means, sleeve member and ring forming with the external surface of the string a longitudinally expansible pressure uid chamber, said ring having an internal bevellcd face positioned to form with the external surface of the string a tapered recess opening into said chamber, wedge means movably disposed inthe recess for movement into wedging engagei for admitting fluid under'pressurefrom the interior of the string into thechamber, means movably disposed in the chamber -to move the wedge means to wedging posiment with Athe ring and string'to' hold the ring againstV74 Y movement in a direction to contract the chamber, means tion in'response'tothe pressure ofiiuidr'in the string, a Y stationary ring on the `string spaced longitudinally from said movable ring, and expansible packer', means around thev ustring Yin position 'for engagement" with said vrings I to 'apply Va compressive force tothe packer means toy exp'andl the packer means into sealing engagement with the string 'and the lsurrounding wall of a Vwell bore upon ex'-Y pansion of said chamber.l

5. In a'well packer, a tubing string,`:a tubular mandrel,

thread means vforming a' rotatable connection betweenrthe mandrel vand an upper section'ofthe tubing string to cause Y mandrel -for` loneitgdinalmvelnent thereafelative toV relativelongitudinal movement of the mandrel and said j section upon rotation of the sectionv relativen` to the mandrel, a sleeve member surroundinglthe mandrel in radially outwardly' spaced relation the'reto,`stationary means surrounding the 'mandrel and closing one end ofthe sleeve Y memberta movable `ring surrounding the mandrel movl Y able with and closing the other end of the sleeve membei", said stationary means', sleeve' 'member and movable ring forming'with the externalV surface of the mandrelV a longitudinally expansible pressure nuid chamber, said ring having an internal,`bevel1ed face positioned to form with the external lsurfacel of'the mandrel a ytapered recess opening into. theV chambefwedge means movably disposed in the recess 4for"n 'lovemen't into wedging engagei ment with the mandrel and ring to'hold .the ring 'againstV seal element', comprising, wedgeshaped anchor elements diseased between the intendi Ofi the lower alilfltlelt member and theeitsrior 0f the mandrel, and Pressure iiuid actuated means movably mounted "on the mandrel cooperating withzsaid anchor elements to urge the same Y into wedenseneaeement betweeatlls lewer. abutment member, and; the raalidrehV meaasfQr directing actuating. pressure uidrfro'm the interior of the mandrel to said last-mentioned means. l Y v 8 '3"Well1paclier, a tubular, mandrel, an annular upper abutmentmember disposed about the mandrel,

an'annular-lower a'bltmllf merrxlerk disposed 'about the the upper4 'abutment member, an annular "seal element disposed about the mandrel between said abutment inembers, 'Saidseal element' being radially expans-ible byyendlwise compression between 'said abutment, members, pressure tluid actuated means having uid pressure communication'with'the" bore of the mandrel positioned on the mandrel to urgej'said lower abutment member Vtoward t the .upper abutment member; to expand said seal element,

wedge-shaped anchorelementsl disposed between the interiorV of the lower abutment member n and the Iexterior of ,the mandrel and yhaving portions lprojecting below s saidlowe'r abutment member, said pressure-duid actuated means' including movable means directly engageable with said projectingportions'of the anchor elements to; urge tbe latter into wedging engagement betweensaid lower of 'saidfseal'elementfv ,i v t 9. In a well packer including' ya tubular mandrel,

abutment member and'thefmandrel to preventV retraction I 'longitudinally' spaced upper and lower abutment'memmovementV infa Y'direction `to` contract the' chamber, means n for admitting iluidunder pressure frornthe interiorof the t mandrel into said chamber to expand the chambenfmeansmovably disposed in ythe 'chamber to urge the i wedge means ltoward wedging position nres'ponse to' the pressure of fluid in vthe" mandrel, la` second lring movably f v mounted on the' mandrel in Vlongitudinally spaced'relation to the rsftring, rnea'ns connectings'aid second ringltosaid vconnection to hold 'the seond'ring against vmovement away from V,said 'first "ring -in' 'on'e-irelati've "longitudinal position of the'mandrel yand said' upper'section'and to allow such Vmovement'of 'said second" ring in another relative longitudinal position'of said mandrel and said upper section.KA

61 Ina Well packer, a tubing string, a tubular mandrel, threadmeans forming a rotatableconnection between the nandr'el'fand an /upper's'ection ofthe tubing' string to cause relative longitudinal movement of the mandrel andsad section uponrotation'of said" section relativeV to the mandrel, longitudinally* spaced' backupf'rings surrounding 4'and movable longitudinally on Athe mandrel, expansible 'packer rnanssurruiiding the 'mandrel'i'be- Vtween said rings, releasable means for initially'holdingl bers surrounding the mandrel, the lowery abutmenty member being movable longitudinally` of the mandrel toward 'thevv upper, .abutment member, f an annular sealv velement fdispo'sed'aboutthe mandrel.for end-wise compression betweentherabutment mem-bers to radially expand the ysealelement, 'means forpreven'ting retraction o f the seal element, comprising, f wedge-'shaped 'anchor' elements disposedbet'ween the"interior`"of the. lower abutment memberandthe exteriorof 'thef mandrel; and pressure iiuid actuated 'mean`s`movably' mounted on thel mandrel co,-

` t operating with" said /anchorelements-.to yurge the same into'wedging engagement betweenthe lower abutment member andj themandrel, means for 'directing actuating pressure fluid from -ther-'interior fof the mandrel* to said lastfmentioned'lmeans, said 'annular seal element com? priising Vupper and'lower. longitudinally spaced annular 'expansible seal' ringsy 'hafving' opposed 'radiallyinwardly converging end surfaces and outer end surfaces engaged by therespective" abutment members,and a centralannular'expansible seal -ring'positioned between and having i inwardly converging end .faces positioned for engagement Y with the converging inner'end surfaces ofsaid upper and one l'of said ringsV against movement 'relative tothe mandrel, pressure'uid' actuated' means" having Vfluid ypressure communication with'the bore of 'themandrel and'positionen onthemandrel to urge said other ring toward said onefring and' to -release saidrreleasable'means in response toV the pressure o-f 'uidin'the mandrel, said rotatable connection including clutch means releasably connecting said upper section of the tubing string to said one of 'said bja'clup rings,Y said clutchv means'being Vreleasable Y by said movement of said other ring Vto'ward'said onering to rlease'said'u'pper section'ifor rotation relative to said mandrel. j

7. InV a well packer including a tubular mandrel, longitudinally spaced upper and lower'abutmentv membersy surrounding theV mandrel, the lower abutment member being movable longitudinally of the mandrel toward the upper abutment member,V an annular seal element disposed about the mandrel' for 'endwise compression between the abutment members to radially expand the Seal element,v means for preventing retraction of the lower YAseal rings.`

i 10. 'In'awell packer, a tubular mandrel, an annular upper abutment member disposed about the 'mandreL an annul'anlowe-r `abutment''m'ernber ydispnsed yabout the mandrel kfor longitudinal movement, thereon'relative to the :upper abutment member, an Vannular sealielement ,t disposed about'the mandrel between saidY abutment members, said 'seal element being radially expansible by endwi's'e compression betweenf'said abutment members, pressure "fluid actufated means having .fluid pressure communication with the Vbore'of the mandrel lpositioned on themandrel toiurge' said lower Yabutment member toward `the upper abutment member to expand said seal element,

of said seal element, said annular seal element comprising upper and lower longitudinal spaced annular expansible seal rings having opposed radially inwardly converging end surfaces and outer end surfaces engaged by Vthe respective abutment members, and a cenral annular expansible seal ring positioned between and having inwardly converging end faces positioned for engagement with the converging inner end surfaces of said upper and lower seal rings.

References Cited in the le of this patent UNITED STATES PATENTS Mack Aug. 24, 1920 Baker Nov. 7, 1939 Fewel Aug. 16, 1955 Brown Sept. 8, 1959 Feeser Apr. 3, 1962 

1. IN A WELL PACKER, A TUBING STRING, A TUBULAR MANDREL, THREAD MEANS FORMING A ROTATABLE CONNECTION BETWEEN THE MANDREL AND AN UPPER SECTION OF THE TUBING STRING TO CAUSE RELATIVE LONGITUDINAL MOVEMENT OF THE MANDREL AND SAID SECTION UPON ROTATION OF THE SECTION RELATIVE TO THE MANDREL, LONGITUDINALLY SPACED BACK-UP RINGS SURROUNDING AND MOVABLE LONGITUDINALLY ON THE MANDREL, EXPANSIBLE PACKER MEANS SURROUNDING THE MANDREL BETWEEN SAID RINGS, RELEASABLE MEANS FOR HOLDING ONE OF SAID RINGS AGAINST MOVEMENT RELATIVE TO SAID MANDREL, AND PRESSURE FLUID 